Boiler and like furnaces



June18, 1935. 5. M. MGNAMARA y BoILER ANDjLIKE FURNACES 2 sheets-sheet 1 Filed March 25, 1952 June '18, 1935. E. M. MCNAMARA 2,005,264

BOILER AND LIKE FURNACES Filed March 25, 1932 2 Shee'os-Sheerl 2 Patented June 18, 1935v UNITED STATES VPATENT OFFICE j Y v 2,005,264 nonna AND LIKE FUaNAcEs yEdward M. McNamara, Chicago, Application March 23, 1932, Serial No. 600,650

- 4 claims. (o1. 11o-40) p I Fig. 4 is a detail sectional top view on line 4 4, f

YThis invention vrelates to that class of steam boiler and like furnaces in Vwhich the lire grates of the type which are adapted to gradually shift the mass of burning fuel tothe rear of the combustion chamber is combined with a fuel feeding unit at the forward portion of said fire grate and withvmeans for introducing into the mass of fuel adjacent to the re grate a plurality of supplies of air to attain a. proper rcombustion of the fuel and its vo-latile elements.

has for its objects: f f A To provide in a furnace in which the fire grate is of any usual type vadapted to progressively move the mass of fuel from the front to the rear end of the combustion chamber, a formation and combinationof parts, especially adapted to effect a very perfect combustion of finely divided bituminous coal, usually the screenings of such form of x fuel now generally used in Yfactories and steam heated buildings in the Middle West Statesr on the ground of economy. The said formation and combination comprising a plurality' of tubes or conduits open at front and rear ends andk extending horizontally through the front wall of theY furnace a distance back of said wall intothe combustion chamber and located above the fire grate, said open ended tubes being adapted to convey a maximum passage of air into the mass of fuel in the combustion chamber to materially aidy in the combustion thereof. The arrangement being such that the portions ofthe bituminous coal surrounding the plurality of tubes during an ordinary combustion thereof will be partially consumed and its particles caked so thatsaid portions of the fuel in leaving the rear ends of said tubes are formed with a like plurality of tunnels or passages adapted to receive supplies of air from said tubes tol materially aid in the combustion of described formation of said tunnels being maintained and strengthened by a further caking of the particles of fuel forming 4the'wall of the tunnels by local combustion therein until the ash formation periodis reached near thev rear and discharge end of the rearwardly moving lire grate, all as will hereinafter more fully appear.

In the accompanying drawings:

Fig. 1 is a detail longitudinal section of the front portion ofy a steam boiler or like furnace having the preferred form of the invention applied thereto. s

Fig. 2 is an enlarged detailsectional elevation of one of the air ducts or tubes, means for supporting same and means for effectingvertical adjustment thereof. n

Fig. 3 is a detail perspective View of thefvertical locking bar by which the supporting means of the air ducts or tubes is secured at the desired adjustment.

And this improvementthe mass of fuel adjacent tothe fire grate, the

Fig. 2.

Fig. 5 is a front elevation of the furnace illustrating the transverse arrangementof parts in` .this invention.

This invention is applicable to any type of` furnace having a rectangular combustion cham-` ber l, the bottom of which is formed by a fire grate 8 of any type adapted to gradually movevthe burning fuel from the front to the rear endlof the combustion chamber..

kAn ordinary endless chain gratek 8 is shown as an exemplication of the above ymentioned type of fire grates. The scope of this'part of the in vention embraces the use instead of said endless chain grate any ofthe ordinary forms of fire grates in which a gradual rearward shift of the burning fuel towards the rear and discharge end of the nre grate is attained. f

In the construction shown in Fig. l, wherein an endless chain re grate 8 constitutes the bottom or floor of the combustion chamber', theflower endwof the front wall 9 of the furnace ends a short distance above the upper surface of the fire grate .to permit the layer of fuel supplied by the fuel feeding hopper hereinafter described, to pass beneath said lower wall end and intothe lili" combustion' chamber in the rearward movement of the top stretch of said chainV grate.

The lhopper from which the crushed fuel `is fed by gravity to the fire grate 8, is mounted on or adjacent to the front wall 9 of the furnace, and preferably comprises a main upper hopper portion I0, and an open bottom lower chuteportion Il in vertically spaced vrelation in order to provideV for a short passage through the lower mass of fuel in said hopper portion I0 and lower chute portion Il, and on the re rgrate 8 of a supply of air to aid in the combustion of the fuel on the adjacent front portion of the combustion chamber.

In the construction shownv in Fig. '1, the lower portion of the front wall of vthe aforesaid chute portion or member Il is formed'by an inclined plate Il of metal, the lower endl of which has separated relation to the top surfacev ofthe firel lar spaced relation to the fire grate 'as thatof the aforesaid inclined front portion l l of' the chute.

A material feature of the rinvention involves'in connection with a furnace construction substantially the same as above described, means for introducing supplies of air for supporting combustion of the fuel in a even and very effective manner embracing the entire fire grate surface, and to such end comprises a formation and arrangement of parts as follows:-

, A longitudinally extending row of air inlet tubes or conduits I2 open at both vends to afford an uninterrupted passage of air to the combustion chamber of the furnace, are associated together in horizontal spaced relation and to such end are fixedly mounted in a carrier head I3, of the plate metal type, and extending the width of the combustion chamber 'I and preferably supported in the adjustable manner hereinafter described by longitudinally arranged bracket plates I4, of the angletype, `ixedly-attached to the inner faces of the side Walls of the furnace. With the described arrangement the plurality of air inlet vtubes or conduits I 2 are positioned in an approximately horizontal plane a distance above the upper surface of the fire grate 8, with their rear portions extending a distance into the combustion chamber 'I as shown.

Arranged as above described, the plurality of air inlet tubes I2 are adapted to constitute cores for an initial formation of a like plurality of longitudinal air tunnels or passages i5 in the mass offuel immediately above the fire grate 8.

The initial formation of the air tunnels I5 above mentioned is attained by a partial agglomeration or coherence of the crushed fuel surrounding the tubes I2 during a partial combustion of the same during the ordinary process of combustion in the furnace,` and before such portions of thefuel leaves the ends of the tubes I2, while the rear open ends ofsaid tubes are adapted to afford an ample supply of air to maintain local combustion of the Walls of said tunnels to more completely agglomerate the walls of the tunnels and maintain such walls intact until the mass of fuel constituting said Walls are by gradual combustion reduced to ashes and be discharged at the lower rear portion of the combustion chamber by the supporting fire grate 8, in the progressive rearward travel of the top stretch of said fire grate.

l With a view to aid in an effective combustion of the volatile elements of the fuel after the entry thereof into the combustion chamber 'I,the sides ofthe air inlet ducts or tubes I2 are formed with one orjmore orifices I2 for affordinglateral and supplementary supplies of air to the fuel adjacent to said orifices to aid in the combustion of the volatile portions of the fuel.

. With a. view to prevent entry of particles offuel into the open rear ends the plurality of air inlet ducts Vor tubes I2 and consequent interference with the free passages of air therethrough, the rear ends of said ducts or tubes have an oblique pr beveledformation as shown, in order that any loose portions of the crushed fuel falling from Ythe `rearward overhanging top portions of the tubes I2 will be received on the bottom portions of the tunnels I5 formed in the manner above `described, in the rearwardly moving mass of fuel, and becarried along with said tunnels and thus prevented from entering the bore of the tubes ,I2 to impede the free rearward passage of air through the same.

The adjustment ofthe plurality of air inlet ducts I2 to and from the re grate 8 is attained in' theconstruction shown in Figs. l to 6, by a pivotal rest or engagement of the lower end corners of the inclined plate metal wall I6 of the carrier head I3 on the bracket plates I4 on the side walls of the furnace, by a notched formation I6' of said lower corners as shown in Fig. 6. And in connection with the above described arrangement of the carrier head I3, a vertically adjustable locking bar I'I is used and which is adapted for manual operation and is formed and arranged as follows:-

The locking bar I'I is arranged for vertical adjustment in the carrier head I3, and is of a flat rectangular shape in cross section and formed with marginal notches I8 adjacent to its respective ends'for engagement in rectangular orifices in the top and bottom walls of the carrier head I3, with the lower ends of the locking bars having a rotary bearing in the aforesaid bracket plates Ill. l

With such construction and with a quarter turn of the locking bars I l in one direction, locking engagement of the notches I8 of said bar with the rectangular orices of the carrier head I3 is effected, with such engagement released by a further quarter turn of the locking bars I'I.

While natural draft of the furnace and its stack may in many cases be relied on for introducing into the combustion chamber I the required amount of air for the proper combustion of the fuel, in many other cases a forced draft may be necessary, and the same can be readily attained by use of the ordinary steam injector nozzles IS, each arranged in central relation to the forward open end of a tube or conduit I2 of the construction shown.

Having thus fully described my invention what I claim as new, is:-

l. The combination in a furnace provided with a combustion chamber, a rearwardly fuel feeding fire grate at the bottom of said chamber, means for feeding crushed fuel to the forward end of said gratefa plurality of air inlet tubes open at both ends and extending through the front wall of said `chamber a distance above the fire grate and a distance inwardly from said wall in aposition to be wholly enveloped in the entering fuel, the tubes so* arranged constituting cores in forming longitudinal air tunnels in the mass ofl fuel in its progressive movement to the rear of the combustion chamber and with said tubes adapted to supply air for local combustion of the Walls of the tunnels, the fire grate being of an endless chain formation.

2. The combination as specified in claim 1, wherein said inlet tubes have their inner open ends of an oblique shape providing upper overhanging end portions adapted to cause the loose fuel particles dropping from the rearwardly overhanging tube portions to drop into the bottom portions of the tunnels so as to be carried rearwardly and prevented from entering the bore of said tubes to impede the flow of air through the tubes into the tunnels.

3. The combination as specified in claim 1, wherein said inlet tubes are provided with means for effecting an adjustment thereof to and from the re grate.

' 4. The combinationv as specied in claim l, wherein a means for effecting an adjustment of said inlet tubes to and from the fire grate comprising a carrier head adjustably mounted at its rear and lower corner on the furnace housing, and means for looking said head at the required adjustment.

EDWARD M. MCNAMARA. 

